Energy absorbing composite panels

Abstract

Typical composite panels are brittle and unable to support transverse pressure loads that might be imposed on the panels. For example, the use of typical panels around fuel tanks of a vehicle are unable to support transverse pressure loads that might be imposed on the fuel tanks during a crash of the vehicle or a ballistic impact to the fuel tanks. In the embodiments described herein, panels include face sheets that are bonded to a foam core. The foam core includes a corrugated core sheet that is formed from a highly ductile material, such as Polyethylene or Aluminum. When a transverse pressure load is imposed on the panel, core crush of the foam occurs as the core sheet elongates from its original corrugated shape to a curve shape during deformation. This allows the panel to dissipate the energy of the transverse pressure load applied to the panel.

What is claimed is: 
     
       1. A composite panel, comprising:
 a first composite laminate; 
 a second composite laminate; 
 a foam core bonded to and interposed between the first composite laminate and the second composite laminate; and 
 a corrugated core sheet within the foam core, wherein the corrugated core sheet has a higher ductility than the first composite laminate and the second composite laminate to absorb energy upon a transverse pressure load imposed on the composite panel. 
 
     
     
       2. The composite panel of  claim 1 , wherein:
 the first composite laminate and the second composite laminate comprise graphite composite laminates; and 
 the corrugated core sheet comprises polyethylene. 
 
     
     
       3. The composite panel of  claim 1 , wherein:
 the first composite laminate and the second composite laminate comprise graphite composite laminates; and 
 the corrugated core sheet comprises aluminum. 
 
     
     
       4. The composite panel of  claim 1 , wherein:
 a thickness of the corrugated core sheet is selected based on pre-defined capability of composite panel to withstand the transverse pressure load during deformation. 
 
     
     
       5. The composite panel of  claim 1 , wherein:
 a shape of the corrugated core sheet comprises a sine wave when viewed through a cross-section through a width of the composite panel. 
 
     
     
       6. The composite panel of  claim 5 , wherein:
 a frequency of the sine wave is selected based on pre-defined capability of the composite panel to withstand the transverse pressure load during deformation. 
 
     
     
       7. The composite panel of  claim 5 , wherein:
 an amplitude of the sine wave is selected based on pre-defined capability of composite panel to withstand the transverse pressure load during deformation. 
 
     
     
       8. A composite structure for a vehicle, the composite structure comprising:
 a plurality of interconnected composite panels, wherein at least one of the plurality of interconnected composite panels comprises: 
 a first composite laminate; 
 a second composite laminate; 
 a foam core bonded to and interposed between the first composite laminate and the second composite laminate; and 
 a corrugated core sheet within the foam core, wherein the corrugated core sheet has a higher ductility than the first composite laminate and the second composite laminate to absorb energy upon a transverse pressure load imposed on the at least one of the plurality of interconnected composite panels. 
 
     
     
       9. The composite structure of  claim 8 , wherein:
 the first composite laminate and the second composite laminate comprise graphite composite laminates; and 
 the corrugated core sheet comprises polyethylene. 
 
     
     
       10. The composite structure of  claim 8 , wherein:
 the first and second composite laminate comprise graphite composite laminates; and 
 the corrugated core sheet comprises aluminum. 
 
     
     
       11. The composite structure of  claim 8 , wherein:
 a thickness of the corrugated core sheet is selected based on pre-defined capability of the at least one of the plurality of interconnected composite panels to withstand the transverse pressure load during deformation. 
 
     
     
       12. The composite structure of  claim 8 , wherein:
 the composite structure forms a structural component of a vehicle. 
 
     
     
       13. The composite structure of  claim 8 , wherein:
 the composite structure encapsulates a fuel bladder of an aircraft. 
 
     
     
       14. The composite structure of  claim 8 , wherein:
 a shape of the corrugated core sheet comprises a sine wave when viewed through a cross-section of a width of the at least one of the plurality of interconnected composite panels. 
 
     
     
       15. The composite structure of  claim 14 , wherein:
 a frequency of the sine wave is selected based on pre-defined capability of the at least one of the plurality of interconnected composite panels to withstand the transverse pressure load ding during deformation. 
 
     
     
       16. The composite structure of  claim 14 , wherein:
 an amplitude of the sine wave is selected based on pre-defined capability of the at least one of the plurality of interconnected composite panels to withstand the transverse pressure load during deformation. 
 
     
     
       17. A composite fuel tank, comprising:
 an internal fuel bladder; and 
 a composite structure encapsulating the internal fuel bladder, the composite structure comprising:
 a plurality of interconnected composite panels, wherein at least one of the plurality of interconnected composite panels comprises:
 a first face sheet; 
 a second face sheet; 
 a foam core bonded to and interposed between the first face sheet and the second face sheet; and 
 a corrugated core sheet within the foam core, wherein the corrugated core sheet has a higher ductility than the first face sheet and the second face sheet to absorb energy upon a transverse pressure load imposed on the at least one of the plurality of interconnected composite panels. 
 
 
 
     
     
       18. The composite fuel tank of  claim 17 , wherein:
 the first face sheet and the second face sheet comprise graphite composite laminates; and 
 the corrugated core sheet comprises polyethylene. 
 
     
     
       19. The composite fuel tank of  claim 17 , wherein:
 the first face sheet and the second face sheet comprise graphite composite laminates; and 
 the corrugated core sheet comprises aluminum. 
 
     
     
       20. The composite fuel tank of  claim 17 , wherein:
 a thickness of the corrugated core sheet is selected based on pre-defined capability of the at least one of the plurality of interconnected composite panels to withstand the transverse pressure load during deformation. 
 
     
     
       21. The composite fuel tank of  claim 17 , wherein:
 a shape of the corrugated core sheet comprises a sine wave when viewed through a cross-section of a width of the at least one of the plurality of interconnected composite panels. 
 
     
     
       22. The composite fuel tank of  claim 21 , wherein:
 a frequency of the sine wave is selected based on pre-defined capability of the at least one of the plurality of interconnected composite panels to withstand the transverse pressure load during deformation. 
 
     
     
       23. The composite fuel tank of  claim 21 , wherein:
 an amplitude of the sine wave is selected based on pre-defined capability of the at least one of the plurality of interconnected composite panels to withstand the transverse pressure load during deformation.